Possible use ofBacillus thuringiensisBerliner as an aid in the biological control of the alfalfa caterpillar

Abstract

This paper is a report on certain aspects of the biological control potentialities of sporeforming bacteria, together with some general considerations of Bacillus thuringiensis Berliner as an insect pathogen. Also reported are recent preliminary field tests on the use of B. thuringiensis as a possible control agent against the alfalfa caterpillar. Results indicate that the bacillus can reduce a destructive insect population to below the economic level. Comparison with earlier results obtained with the polyhedrosis virus shows that the bacillus acts more quickly and leaves the integument of the insect intact, thus preventing smearing of the host plant, but that it does not reduce the population as consistently to as low a point as the virus. A combination of the two agents may possibly offer the greatest overall efficiency of control.